DDR2 800mhz running at 667mhz?

[iceisles]

Hey all - I just built a new system and am using 2 GB of Corsair PC2-6400 DDR2 800MHz. For some reason, my BIOS is defaulting this to run at a DRAM frequency of 667mhz. Do you have any idea why this might be?

I'm not an overclocker, but I am familiar with the BIOS and know how to change this on my motherboard (ASUS P5B Deluxe). However, is it safe to maually change the DRAM frequency to DDR-800 even though the BIOS is defaulting lower?

I just want to make sure that adjusting the memory speed won't negatively impact my computer (Core™ 2 Duo E6600 ) in any way. I'm not looking to overclock, so will bumping up the DRAM frequency make the processor run faster than its rated?

As a first time poster, I really appreciate your help.

 

[sruane]

.... However, is it safe to maually change the DRAM frequency to DDR-800 even though the BIOS is defaulting lower?

....

yes.

 

[powerbaselx]

Hey all - I just built a new system and am using 2 GB of Corsair PC2-6400 DDR2 800MHz. For some reason, my BIOS is defaulting this to run at a DRAM frequency of 667mhz. Do you have any idea why this might be?

Yes. Your DDR2 frequency is now at 667MHz (bus=333MHz.)
That freq is probably set by the SPD.

However, is it safe to maually change the DRAM frequency to DDR-800 even though the BIOS is defaulting lower?

Yes, it is safe.

I just want to make sure that adjusting the memory speed won't negatively impact my computer (Core™ 2 Duo E6600 ) in any way. I'm not looking to overclock, so will bumping up the DRAM frequency make the processor run faster than its rated?

Probably yes since you must set the bus speed to 400Mhz to achieve DDR2 freq 800MHz.

As a first time poster, I really appreciate your help.

Welcome. Hope it helps.

 

[sruane]

I just want to make sure that adjusting the memory speed won't negatively impact my computer (Core™ 2 Duo E6600 ) in any way. I'm not looking to overclock, so will bumping up the DRAM frequency make the processor run faster than its rated?

Probably yes since you must set the bus speed to 400Mhz to achieve DDR2 freq 800MHz.

As a first time poster, I really appreciate your help.

Welcome. Hope it helps.

Only if the memory multiplier is 2. If the memory multiplier us 3, the bus can ruin at 266MHz. At 2.5 its 320

 

[rushfan]

Hey all - I just built a new system and am using 2 GB of Corsair PC2-6400 DDR2 800MHz. For some reason, my BIOS is defaulting this to run at a DRAM frequency of 667mhz. Do you have any idea why this might be?

I'm not an overclocker, but I am familiar with the BIOS and know how to change this on my motherboard (ASUS P5B Deluxe). However, is it safe to maually change the DRAM frequency to DDR-800 even though the BIOS is defaulting lower?

I just want to make sure that adjusting the memory speed won't negatively impact my computer (Core™ 2 Duo E6600 ) in any way. I'm not looking to overclock, so will bumping up the DRAM frequency make the processor run faster than its rated?

As a first time poster, I really appreciate your help.

As somebody else mentioned, the SPD chip on your RAM is probably reporting 667 MHz thought the RAM itself is tested and rated for 800 MHz. All that you need to do is to change the setting manualy in the BIOS.

Changing the FSB to 400 MHz is not the same thing. Both the CPU and RAM run off the FSB so you would be overclocking your CPU at that point while the RAM would be right-clocked. Your CPU can probably take the 400 MHz FSB. If overclocking interests you, there are lots of threads and stickys in this forum that will guide you.

 

[iceisles]

Wow, I love the quick replies on here! I will go ahead and manually change the DRAM to run at 800mhz, but like sruane mentioned, I will essentially be overclocking since the bus speed needs to be bumped to 400Mhz? I'm not overly concerned since this setup is a known to be solid at handling such demands.

As much as I've researched, I don't fully understand how the CPU FSB & RAM frequencies are connected. I know it has something to do with ratios, etc. Is there a good guide for newbies like myself that can explain this a little better?

 

[sruane]

Wow, I love the quick replies on here! I will go ahead and manually change the DRAM to run at 800mhz, but like sruane mentioned, I will essentially be overclocking since the bus speed needs to be bumped to 400Mhz? I'm not overly concerned since this setup is a known to be solid at handling such demands.

The bus speed does not need to be raised to 400MHz, in fact - I'd advise against it. Running the bus that fast will require that you make several other tweaks. Your best bet is to just change the memory multiplier.

 

[iceisles]

Wow, I love the quick replies on here! I will go ahead and manually change the DRAM to run at 800mhz, but like sruane mentioned, I will essentially be overclocking since the bus speed needs to be bumped to 400Mhz? I'm not overly concerned since this setup is a known to be solid at handling such demands.

The bus speed does not need to be raised to 400MHz, in fact - I'd advise against it. Running the bus that fast will require that you make several other tweaks. Your best bet is to just change the memory multiplier.

Will changing the memory multiplier alter the CPU in any way? I'm figuring ASUS is defaulting the RAM to 667 for a reason.

 

[sruane]

Wow, I love the quick replies on here! I will go ahead and manually change the DRAM to run at 800mhz, but like sruane mentioned, I will essentially be overclocking since the bus speed needs to be bumped to 400Mhz? I'm not overly concerned since this setup is a known to be solid at handling such demands.

The bus speed does not need to be raised to 400MHz, in fact - I'd advise against it. Running the bus that fast will require that you make several other tweaks. Your best bet is to just change the memory multiplier.

Will changing the memory multiplier alter the CPU in any way? I'm figuring ASUS is defaulting the RAM to 667 for a reason.

No.

 

[iceisles]

How do I go about changing just the memory multiplier in the BIOS? I assume I have to keep SPD disabled (which I did anyway to correct the CAS ratings). Ideally, I want to leave the board FSB's alone and just have the RAM run at the speed it's rated for. Thanks for your help.

 

[zjohnr]

FWIW, if your are not overclocking and your RAM is running at 667MHz then your memory multiplier has already been changed from 1:1 to something like 4:5 CPURAM.

Have you looked at what CPU-Z reports for your system?? In particular, I'd be curious what CPU-Z reports about the DRAM's speed and SPD settings. Not sure why everyone else is speculating about what your SPD does or does not contain when you can just run CPU-Z and find out ... :? If this is DDR2-800 RAM then I would expect there would be SPD settings for 400MHz (as well as 333 and 266).

Whatever. Why not just look and see?

-john, the ostensibly clueless redundant legacy dinosaur

 

[iceisles]

FWIW, if your are not overclocking and your RAM is running at 667MHz then your memory multiplier has already been changed from 1:1 to something like 4:5 CPURAM.

Have you looked at what CPU-Z reports for your system?? In particular, I'd be curious what CPU-Z reports about the DRAM's speed and SPD settings. Not sure why everyone else is speculating about what your SPD does or does not contain when you can just run CPU-Z and find out ... :? If this is DDR2-800 RAM then I would expect there would be SPD settings for 400MHz (as well as 333 and 266).

Whatever. Why not just look and see?

-john, the ostensibly clueless redundant legacy dinosaur

Thanks, John - I'll take a look and see. In the meantime, if I change my memory multipiler to 3, the FSB will still run at 266Mhz (stock speed ), correct? My goal is to keep the system at 2.4Ghz, 266Mhz FSB, with the DRAM at 800Mhz. Would this be a 1:1 ratio?

 

[xeni]

FWIW, if your are not overclocking and your RAM is running at 667MHz then your memory multiplier has already been changed from 1:1 to something like 4:5 CPURAM.

Have you looked at what CPU-Z reports for your system?? In particular, I'd be curious what CPU-Z reports about the DRAM's speed and SPD settings. Not sure why everyone else is speculating about what your SPD does or does not contain when you can just run CPU-Z and find out ... :? If this is DDR2-800 RAM then I would expect there would be SPD settings for 400MHz (as well as 333 and 266).

Whatever. Why not just look and see?

-john, the ostensibly clueless redundant legacy dinosaur

Thanks, John - I'll take a look and see. In the meantime, if I change my memory multipiler to 3, the FSB will still run at 266Mhz (stock speed ), correct? My goal is to keep the system at 2.4Ghz, 266Mhz FSB, with the DRAM at 800Mhz. Would this be a 1:1 ratio?

That is correct. I have the same memory as you do and i am running it at a 1:1 multiplyer and thats because i have my system overclocked. But since your not overclocking keep it on the multiper 3 ratio.

 

[iceisles]

FWIW, if your are not overclocking and your RAM is running at 667MHz then your memory multiplier has already been changed from 1:1 to something like 4:5 CPURAM.

Have you looked at what CPU-Z reports for your system?? In particular, I'd be curious what CPU-Z reports about the DRAM's speed and SPD settings. Not sure why everyone else is speculating about what your SPD does or does not contain when you can just run CPU-Z and find out ... :? If this is DDR2-800 RAM then I would expect there would be SPD settings for 400MHz (as well as 333 and 266).

Whatever. Why not just look and see?

-john, the ostensibly clueless redundant legacy dinosaur

Thanks, John - I'll take a look and see. In the meantime, if I change my memory multipiler to 3, the FSB will still run at 266Mhz (stock speed ), correct? My goal is to keep the system at 2.4Ghz, 266Mhz FSB, with the DRAM at 800Mhz. Would this be a 1:1 ratio?

That is correct. I have the same memory as you do and i am running it at a 1:1 multiplyer and thats because i have my system overclocked. But since your not overclocking keep it on the multiper 3 ratio.

Thanks, xeni. What does the memory multiplier essentially do? Is it simply telling only the RAM to operate at a different speed relative to the FSB (i.e., 2 x 266, 3 x 266, etc.)?

 

[Nova46]

I have the same issue. Well, not really issue cause I know how to fix it but I have a question.

I've heard it's more stable to run your CPURAM ratio at 1:1 than some other weird ratio. My E6600 is running at 3.0 Ghz, 333 Mhz bus speed and so my memory is running at DDR2-667. Would it be better to leave it as it is now or change the ratio and run my memory at DDR2-800 like it's rated for?

 

[iceisles]

I have the same issue. Well, not really issue cause I know how to fix it but I have a question.

I've heard it's more stable to run your CPURAM ratio at 1:1 than some other weird ratio. My E6600 is running at 3.0 Ghz, 333 Mhz bus speed and so my memory is running at DDR2-667. Would it be better to leave it as it is now or change the ratio and run my memory at DDR2-800 like it's rated for?

From what I've read, 1:1 is the way to go, but it seems that involves at least some degree of overclocking. The other posters can correct me if I'm wrong, but the Core 2 Duo's seem to have a negligible performance increase in memory speeds above 533Mhz. I probably could keep mine at 667, but I kinda feel like I'm not getting what I paid for if it's not running at full capacity.

 

[zjohnr]

In the meantime, if I change my memory multipiler to 3, the FSB will still run at 266Mhz (stock speed ), correct? My goal is to keep the system at 2.4Ghz, 266Mhz FSB, with the DRAM at 800Mhz. Would this be a 1:1 ratio?

My arithmetic is different. I get 400MHz = 1.5*266MHz or a memory multiplier of 1.5. I don't think the memory multiplier is typically specified this easily though. Usually the motherboard manufacturer will try to "help" by either allow you to pick from a list of CPURAM ratios (266:400 or 2:3 being what you'd want in this case) or, as Asus appears to do, giving you a list of memory freqs to pick from.

Info about changing the memory multiplier should be coved in the Asus P5B Deluxe owner's manal. (If you can't find yours you can download it from Asus. Here's a link to the Asus download page). I just glanced through the manual quickly so I'm not positive, but I think that the memory multiplier is set under "JumperFree Configuration". (Page 87 in my downloaded copy). Here is what I think is the path to this setting in the BIOS: Main->Advanced->JumperFree Configuration ... DRAM Frequency

The default setting is "Auto". Other choices appear to be DDR2-533, DDR2-667, DDR2-800, DDR2-899, DDR2-1067. All of these of course assume that you have set the CPU Frequency to either Auto or 266 (i.e. no overclocking).

-john, the ostensibly clueless redundant legacy dinosaur

 

[rushfan]

Not sure why everyone else is speculating about what your SPD does or does not contain when you can just run CPU-Z and find out ... :?

Some DDR2 modules only have SPD settings to 333 MHz even though they are rated for 400 MHz operation. The Kingston Hyper-X memory that I use is an example of that. CPU-Z reports that it is rated for 333 MHz maximum even though it is tested, marketed and sold as 800 MHz memory.

 

[Mondoman]

...
I've heard it's more stable to run your CPURAM ratio at 1:1 than some other weird ratio.

Nope; weird ratios are stable, too.

y E6600 is running at 3.0 Ghz, 333 Mhz bus speed and so my memory is running at DDR2-667. Would it be better to leave it as it is now or change the ratio and run my memory at DDR2-800 like it's rated for?

The main thing is to be running in dual-channel mode at at least a 1:1 ratio. If you speed up the memory one notch (as you suggest), it probably won't make a big performance difference. Speeding up the memory two or more notches will make a more substantial difference.

 

[zjohnr]

I've heard it's more stable to run your CPURAM ratio at 1:1 than some other weird ratio.

Nope; weird ratios are stable, too.
Yes, weird ratios are stable in the sense that you shouldn't crash or BSOD your system. But there is also apparently some performance weirdness.

Not quite a week ago in another thread someone else pointed me towards this Madshrimps article: Intel Core 2: Is high speed memory worth its price? Basically there take an E6700, 2GB of fast OCZ DDR2-900 PC7200, and an Intel D975XBX motherboard and see what happens running the same benchmarks with the CPU at stock 266MHz speed while varying the memory speed and timing settings in the BIOS.

What's surprising is that they don't always see a performance increase when one would naively expect one. For example, when they compare DDR2-533(4-4-4-12) to DDR2-667(5-5-5-15) the total latencies should be approximately the same. And if the latencies are the same, I would expect the higher freq DDR2-667 to perform slightly better than the DDR2-533. However, they actually measure a slight drop in the performance results for their Super-Pi and the Photoshop benchmarks.

In other words, something a little funky seems to happen when running the DRAM one "notch" (?) above the FSB speed.

Don't know what, if anything, to conclude from this article. It's probably important to remember that whatever differences they did notice were all very small. No one is likely to notice a performance difference on the order of 5% or less other than by measuring it. Human perceptions are just not that finely honed.

I also wonder what would happen if this test were run against an Intel P965 chipset motherboard instead of the P975 chipset. Probably not a significant factor, but I still wonder.

-john, the ostensibly clueless redundant legacy dinosaur.

 

[cookin]

The last paragraph of the Madshrimps article zjohnr refers to does say that 667 memory may actually not be a benefit if not overclocking, but it goes on to say:

Why is PC6400, which is also running asynchronous, faster then? Because the memory speed is now that much higher that it compensates for the loss of running asynchronous and overall performance does increase .

http://www.madshrimps.be/?action=getarticle&number=4&artpage=1965&articID=472

 

[iceisles]

A few articles I've read strongly discourage increasing the FSB to 400 on this board. If I want to keep the FSB at 266, is my only option to run at a ratio other than 1:1? And is that really a bad thing? Obviously 1:1 will yield the best performance on benchmarks, but would the normal user notice any difference?

 

[zjohnr]

A few articles I've read strongly discourage increasing the FSB to 400 on this board. If I want to keep the FSB at 266, is my only option to run at a ratio other than 1:1? And is that really a bad thing?

Well, if you are not overclocking then you will always be a long way away from a 400MHz FSB. The FSB and the memory bus are two different things. They are interconnected only in that the speed the memory bus is run at is derived from the FSB speed. Hence the "ratios".

If you want to run the FSB at the stock setting of 266MHz then, yes, the only way to run the memory faster than 266MHz (which is DDR2-533) is to use a ratio other than 1:1.

But no, you are not likely to ever notice the performance difference between any of these settings. We're talking differences of a few percent here. If you had an application that took an hour of CPU and memory intensive crunching to complete, a 5% performance improvement would allow it to complete 3 minutes faster or in 57 rather than 60 minutes. We're talking about performance differences less than 5% so the gain would actually be less.

People tend to spend a lot of money for high performance memory. But the money spent is usually not worth the performance they actually gain. An exception to this would be if they overclocked. But the performance gain in that case is not from the faster memory but because the processor is running faster.

Like I said earlier, the best thing to do is probably to run CPU-Z and see what it says about how fast your CPU and memory are running and also what SPD settings your memory comes with. When you get a chance to do that post the numbers and we can discuss this further if you wish.

-john, the ostensibly clueless rudundant legacy dinosaur

 

[powerbaselx]

People tend to spend a lot of money for high performance memory. But the money spent is usually not worth the performance they actually gain. An exception to this would be if they overclocked. But the performance gain in that case is not from the faster memory but because the processor is running faster.

That is true. Expensive memory is important for OC'ers because it introduces more flexibility abling to reach higher CPU speeds. Especially if you have a mobo that allows only changing the bus speed (fixed cpu and dram multipliers) or you have a mobo that allows you to reach higher mem speeds.
The gain is in the CPU OC and bus speed increase, and not on the memory only by itself.

For a common user or a light-OC'ers, DDR2-533 or DDR2-667 is more than enough and what really matters is that you either install 1GB or 2GB capacity (or more!).

 

[markdixon]

If you want to run the FSB at the stock setting of 266MHz then, yes, the only way to run the memory faster than 266MHz (which is DDR2-533) is to use a ratio other than 1:1.

Sorry about the hijack but I thought I had this figured out and now am confused again (all I'm trying to figure out is the fastest/most economical 2 x 1G RAM for msi P965 mb that will never be oc).

The msi site says "p965 fsb 533, 800, 1066" - does this mean I get to pick between those 3 speeds for fsb? But I'm confused because if ppl are saying 'fsb 400 is pushing it' how come the lowest fsb on p965 is substantially higher than 400?

I'm also confused (again) because:

1) should I be getting DDR2-533 because this is 1:1 what the lowest p965 fsb can be set to (533MHz) or because

2) it's not really fsb 533MHz but 266MHz and DDR2-533 is 2x that or because

3) DDR2-533 is half the highest fsb can be set to (1066MHz)?

Really, all I'm after is trying to determine the fastest, least expensive and most reliable RAM I can get for this board but after all this reading I know less than when I started

Thank you.